If seeking to frames is good enough for random seeking, this can be done with zeekstd already. The cli sets a custom window log (ZSTD_c_windowLog) on the compression context when creating binary patches[1], I regularly use it with a window size above 1G.

[1] https://github.com/rorosen/zeekstd/blob/main/cli/src/compres...

Nice, thanks.